"""Pipeline health watchdog — detects stalls and model failures fast.

Runs every 60 seconds (inside the existing health check or as its own stage).
Checks for conditions that have caused pipeline stalls:

1. Eval stall: open PRs with tier0_pass=1 but no eval event in 5 minutes
2. Breaker open: any circuit breaker in open state
3. Model API failure: 400/401 errors indicating invalid model ID or auth failure
4. Zombie accumulation: PRs with exhausted fix budget sitting in open

When a condition is detected, logs a WARNING with specific diagnosis.
Future: could trigger Pentagon notification or webhook.

Epimetheus owns this module. Born from 3 stall incidents in 2 sessions.
"""

import json
import logging
from datetime import datetime, timezone

from . import config, db

logger = logging.getLogger("pipeline.watchdog")


async def watchdog_check(conn) -> dict:
    """Run all health checks. Returns {healthy: bool, issues: [...]}.

    Called every 60 seconds by the pipeline daemon.
    """
    issues = []

    # 1. Eval stall: open PRs ready for eval but no eval event in 5 minutes
    eval_ready = conn.execute(
        """SELECT COUNT(*) as n FROM prs
           WHERE status = 'open' AND tier0_pass = 1
           AND domain_verdict = 'pending' AND eval_attempts < ?""",
        (config.MAX_EVAL_ATTEMPTS,),
    ).fetchone()["n"]

    if eval_ready > 0:
        last_eval = conn.execute(
            "SELECT MAX(timestamp) as ts FROM audit_log WHERE stage = 'evaluate'"
        ).fetchone()
        if last_eval and last_eval["ts"]:
            try:
                last_ts = datetime.fromisoformat(last_eval["ts"].replace("Z", "+00:00"))
                age_seconds = (datetime.now(timezone.utc) - last_ts).total_seconds()
                if age_seconds > 300:  # 5 minutes
                    issues.append({
                        "type": "eval_stall",
                        "severity": "critical",
                        "detail": f"{eval_ready} PRs ready for eval but no eval event in {int(age_seconds)}s",
                        "action": "Check eval breaker state and model API availability",
                    })
            except (ValueError, TypeError):
                pass

    # 2. Breaker open
    breakers = conn.execute(
        "SELECT name, state, failures FROM circuit_breakers WHERE state = 'open'"
    ).fetchall()
    for b in breakers:
        issues.append({
            "type": "breaker_open",
            "severity": "critical",
            "detail": f"Breaker '{b['name']}' is OPEN ({b['failures']} failures)",
            "action": f"Check {b['name']} stage logs for root cause",
        })

    # 3. Model API failure pattern: 5+ recent errors from same model
    recent_errors = conn.execute(
        """SELECT detail FROM audit_log
           WHERE stage = 'evaluate' AND event IN ('error', 'domain_rejected')
           AND timestamp > datetime('now', '-10 minutes')
           ORDER BY id DESC LIMIT 10"""
    ).fetchall()
    error_count = 0
    for row in recent_errors:
        detail = row["detail"] or ""
        if "400" in detail or "not a valid model" in detail or "401" in detail:
            error_count += 1
    if error_count >= 3:
        issues.append({
            "type": "model_api_failure",
            "severity": "critical",
            "detail": f"{error_count} model API errors in last 10 minutes — possible invalid model ID or auth failure",
            "action": "Check OpenRouter model IDs in config.py and API key validity",
        })

    # 4. Zombie PRs: open with exhausted fix budget and request_changes
    zombies = conn.execute(
        """SELECT COUNT(*) as n FROM prs
           WHERE status = 'open' AND fix_attempts >= ?
           AND (domain_verdict = 'request_changes' OR leo_verdict = 'request_changes')""",
        (config.MAX_FIX_ATTEMPTS,),
    ).fetchone()["n"]
    if zombies > 0:
        issues.append({
            "type": "zombie_prs",
            "severity": "warning",
            "detail": f"{zombies} PRs with exhausted fix budget still open",
            "action": "GC should auto-close these — check fixer.py GC logic",
        })

    # 5. Tier0 blockage: many PRs with tier0_pass=0 (potential validation bug)
    tier0_blocked = conn.execute(
        "SELECT COUNT(*) as n FROM prs WHERE status = 'open' AND tier0_pass = 0"
    ).fetchone()["n"]
    if tier0_blocked >= 5:
        issues.append({
            "type": "tier0_blockage",
            "severity": "warning",
            "detail": f"{tier0_blocked} PRs blocked at tier0_pass=0",
            "action": "Check validate.py — may be the modified-file or wiki-link bug recurring",
        })

    # Log issues
    healthy = len(issues) == 0
    if not healthy:
        for issue in issues:
            if issue["severity"] == "critical":
                logger.warning("WATCHDOG CRITICAL: %s — %s", issue["type"], issue["detail"])
            else:
                logger.info("WATCHDOG: %s — %s", issue["type"], issue["detail"])

    return {"healthy": healthy, "issues": issues, "checks_run": 5}


async def watchdog_cycle(conn, max_workers=None) -> tuple[int, int]:
    """Pipeline stage entry point. Returns (1, 0) on success."""
    result = await watchdog_check(conn)
    if not result["healthy"]:
        db.audit(
            conn, "watchdog", "issues_detected",
            json.dumps({"issues": result["issues"]}),
        )
    return 1, 0